CN8478 Datasheet, PDF (180/221 Pages) Conexant Systems, Inc – Multichannel Synchronous Communications Controller (MUSYCC)

6.0 Basic Operation
6.4 Protocol Support
CN8478/CN8474A/CN8472A/CN8471A
Multichannel Synchronous Communications Controller (MUSYCC™)
6.4.9.4 Receive Errors
Overflow Due to Host
Ownership of the Buffer
(ONR)
Overflow Due to Internal FIFO
Buffer Overrun (BUFF)
Receive errors are service-affecting and may require a corrective action by a
controlling device to resume normal bit-level processing.
In the case of overflow due to host ownership of the buffer, the host has not
provided sufficient data buffer space to store received data from the serial
interface, and the internal FIFO buffer overflows with received data bits.
Reasons:
• Degradation of the host subsystem or application software performance.
• Congestion of the PCI bus.
Effects:
• The Interrupt Descriptor in Interrupt Queue with ERROR = ONR,
DIR = 0.
• The received data in the internal FIFO buffer is discarded and lost to the
host.
• The channel is deactivated.
Channel Level Recovery Actions:
• Reactivate the channel.
In the case of overflow due to internal FIFO buffer overrun, the internal FIFO
buffer is not completely copied to shared memory before more received data bits
must be stored in the FIFO buffer. MUSYCC has access to a shared memory
buffer in this case.
Reasons:
• Degradation of the host subsystem or application software performance.
• Congestion of the PCI bus.
Effects:
• MUSYCC writes the Interrupt Descriptor in Interrupt Queue with
ERROR = BUFF, DIR = 0.
• The received data in the internal FIFO is discarded and lost to the host.
• No additional activity on the PCI bus for this channel direction.
• Receive channel activity is suspended.
Channel Level Recovery Actions:
• If possible, increase internal FIFO buffer space for this channel.
• Alleviate loading of the PCI bus.
• Reactivate receive channel with a channel activate or channel jump service
request or with a slave write into the Receive Channel Configuration
Table.
6-46
Conexant
100660E